The truck driver blasts the horn. He's ready to go.
Huddled under a canopy nearby to escape the smoldering midday sun, a team of observers ready their equipment -- straightening camera straps and clicking away on computer keyboards. What they've come to see will only take about a minute, but it's the culmination of months (and sometimes years) of work. They want to be ready.
The driver slowly advances the small, cobalt flatbed truck down the straight track stretched out in front of him. A cable bound in pulleys and attached to the truck's hitch extends behind the bed and parallels the truck back down the track, where it's affixed to the front of another small truck (this one white and with the phrase "Fighting Terrorism Together" affixed to the side).
The cobalt truck pulls the white truck forward, steadily increasing speed until the white truck reaches 30 mph. The observers begin clicking their cameras, capturing digital images and video only moments before the white truck slams head first into the granite barrier, coming to rest in a cloud of dust and debris.
The collision isn't unexpected. In fact, it's a meticulously planned and executed series of events led by Penn State Thomas D. Larson Pennsylvania Transportation Institute faculty and staff, who are using technology to help design safety barriers that protect U.S. embassies overseas.
Charged with safeguarding U.S. assets domestically and abroad, the U.S. Department of State awarded the Larson Institute a multi-million dollar award in 2010 to conceptualize, research, simulate, build and test safety barriers like those seen in front of monuments, memorials and the White House. Crash tests conducted at the Larson Institute's test track facility -- a 1-mile, oval roadway surrounded by farmland and located roughly 6 miles north of University Park campus -- are one of the later steps in the process.
Zoltan Rado, senior research associate at the Larson Institute in the College of Engineering, has been leading the team of faculty and staff working on the project for the past five years and was involved in the barrier design process from the beginning.
"When staff in the State Department go abroad to build a new embassy, they are facing local codes and requirements that define what they can do with the safety barriers for the building -- how far outside the property they can go, how deep they can dig and parameters around what the barriers can look like," said Rado. "After they know what restrictions they have, they contact us and we start conceptualizing different possibilities as a team. It actually starts off very rudimentary, with just a pencil and some paper."
After weeding out the unattractive designs, Larson Institute and State Department staff collaborate on a final plan -- one that's both feasible to build and fulfills the State Department's restrictions for each particular building.
"Once we have the final design, we create engineering drawings, which are used for construction and manufacturing," said Rado. "The parameters of these drawings are entered into special simulation software, which allows us to reproduce the crash electronically before building anything with physical materials."
This high-quality simulation software, called LS-DYNA, allows Rado and his staff to emulate and manipulate the conditions of every single property within the proposed barrier design -- from the size and weight of the barrier to the type of soil it will be partially buried in.
"LS-DYNA divides every structure we are testing into tiny elements, and then they have tiny elements and so on," said Rado. "There are hundreds of thousands of elements in this engineering drawing once it's entered into the software, and each one can affect the outcome of a simulated crash. We need to make sure we're very precise when using LS-DYNA, or it could completely throw off our expected success when we move to a physical test."
Tong Qiu, associate professor of civil engineering, said the team will collaborate with the State Department to move ahead with a crash test if the simulation results indicate the proposed barrier will pass test criteria defined by ASTM International.
"ASTM International has three criteria for passing a test -- P1, P2 and P3, with P1 being the most strict," said Qiu. "To pass the P1 criteria, which is what we try to do, the vehicle cannot penetrate more than 1 meter beyond the barrier when it crashes into the barrier going either 30 mph or 50 mph, depending on the type of barrier that's being tested."
Barriers, like the crash vehicles at the Larson Institute's test track, can come in all shapes and sizes. Qiu, Rado and the rest of the team focus on two types of barrier designs: landscape and streetscape.
"Landscape barriers are what most people think of when they think of safety barriers -- thick slabs of concrete lined up together in front of what needs protection," said Rado. "Some countries require a barrier that blends into the scenery better, so they want streetscape barriers. These barriers look nondescript, like a bench or street light, but they can withstand the force of a heavy vehicle."
Back at the test track, staff, graduate students and a State Department representative evaluate the landscape barrier to see how it held up to the impact of the white truck. The flowers the team placed around the barrier, just as they would be at a State Department site, lay scattered on their sides, still in their plastic pots, having been run over during the test.
Circling the barrier, which is partially imbedded in mulch-topped soil, the researchers take note of how close to a white chalk line -- the ASTM test indicator -- the truck pushed the barrier. This particular barrier seems to have passed the P1 rating criteria. Once approved for use, it will join the rest of the Larson Institute's barriers in a catalog the State Department provides for existing and future U.S. embassies.
"We've designed several barrier systems with the State Department," said Qiu. "They give us a lot of freedom to explore ideas, and we've given them a lot of things they can use to protect people around the world. The collaboration between the State Department and Penn State has been fantastic, and we're excited that our work is helping so many others."
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